40 to 60 million years is the age given for the rock from which the hoodoos were carved, by the Old Earthers who wrote the article for the National Park Service, whom I suppose to be real people, but I suppose they could be robots programmed to spout OE stuff.
And the age of the
rock is different from the age of the
hoodoos. This is why I asked you for an instance of someone giving an erroneous date for any given hoodoo, rather that of someone giving an accurate date for the rock.
Do you have some reason to suppose that the hoodoos didn't start eroding at that point?
Yes. For starters, if the hoodoos we have now had started being formed then, they wouldn't still be here.
You can read some interesting stuff about hoodoo formation
here.
The hoodoos have limited life-spans. What you see toward the top of the image is remnants of hoodoos, now transformed into the rounded hill erosions one would expect if normal arroyo wash processes had been dominant throughout. As Sprinkel et al. observe, the rim of Bryce Canyon is a passive topographic feature that retreats backward, estimated at about 4 feet per century, which would add up to 12 miles in a million years....